diff --git a/classes/ComicPressStoryline.inc b/classes/ComicPressStoryline.inc
index ffeb2e4..c19264c 100644
--- a/classes/ComicPressStoryline.inc
+++ b/classes/ComicPressStoryline.inc
@@ -412,7 +412,9 @@ class ComicPressStoryline {
 	}
 
   function &include_all() {
-    $this->_category_search = array_keys($this->_structure);
+  	if (is_array($this->_structure)) {
+    	$this->_category_search = array_keys($this->_structure);
+  	}
     return $this;
   }